The diabetes mortality rate among American Indians is 2 to 3 times that of the United States population, all races. The diabetes mortality rate in the Aberdeen Area of Indian Health Service (AAIHS) exceeds the general U.S. population rate by 5.2 times (OTA). Lower extremity amputation (LEA) is a serious complication of non-insulin dependent diabetes (NIDDM). In the AAIHS, the rate of LEA among diabetic persons is nearly double the diabetes-related LEA rate in the United States general population. The design of preventive measures requires that information regarding risk factors for LEA among diabetics be available. However, only the ongoing study of the Pimatribe in the southwestern United States has generated published data specific to LEA within a Native American population. The purpose of this study will be to identify risk factors associated with LEA among members of the Sioux tribe. Utilizing a case-control design, existing data will be extracted from medical records for 281 cases and 281 controls. Cases (persons with NIDDM-related LEA) will be identified through the AAIHS Diabetes Control Program (DCP); controls (persons with NIDDM, but without LEA) will be identified through diabetic registries at 10 Service Units of AAIHS. Odds ratios with 95 per cent confidence intervals will be calculated for identified variables. Multiple logistic regression analysis will be applied to analyze individual and joint effects of identified variables on the risk of LEA. The regression analysis will utilize one half of the sample, which will be selected randomly from the entire sample of cases and controls. External validation of the model equation will then be tested for its ability to predict LEA within the second half of the sample.